Millimeter (mm): The millimeter is equal to one one-thousandth of a meter (0.001 meters). It is frequently used for very precise measurements, such as the thickness of paper or the diameter of small objects.
Micrometer (µm): The micrometer, also known as the micron, is equal to one one-millionth of a meter (0.000001 meters). It is used in scientific research, especially in fields like microscopy and nanotechnology.